1 /* 2 * Copyright (c) 1991 Regents of the University of California. 3 * All rights reserved. 4 * Copyright (c) 1994 John S. Dyson 5 * All rights reserved. 6 * Copyright (c) 1994 David Greenman 7 * All rights reserved. 8 * 9 * This code is derived from software contributed to Berkeley by 10 * The Mach Operating System project at Carnegie-Mellon University. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * This product includes software developed by the University of 23 * California, Berkeley and its contributors. 24 * 4. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 * 40 * from: @(#)vm_pageout.c 7.4 (Berkeley) 5/7/91 41 * 42 * 43 * Copyright (c) 1987, 1990 Carnegie-Mellon University. 44 * All rights reserved. 45 * 46 * Authors: Avadis Tevanian, Jr., Michael Wayne Young 47 * 48 * Permission to use, copy, modify and distribute this software and 49 * its documentation is hereby granted, provided that both the copyright 50 * notice and this permission notice appear in all copies of the 51 * software, derivative works or modified versions, and any portions 52 * thereof, and that both notices appear in supporting documentation. 53 * 54 * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS" 55 * CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND 56 * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE. 57 * 58 * Carnegie Mellon requests users of this software to return to 59 * 60 * Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU 61 * School of Computer Science 62 * Carnegie Mellon University 63 * Pittsburgh PA 15213-3890 64 * 65 * any improvements or extensions that they make and grant Carnegie the 66 * rights to redistribute these changes. 67 * 68 * $FreeBSD$ 69 */ 70 71 /* 72 * The proverbial page-out daemon. 73 */ 74 75 #include "opt_vm.h" 76 #include <sys/param.h> 77 #include <sys/systm.h> 78 #include <sys/kernel.h> 79 #include <sys/lock.h> 80 #include <sys/mutex.h> 81 #include <sys/proc.h> 82 #include <sys/kthread.h> 83 #include <sys/ktr.h> 84 #include <sys/resourcevar.h> 85 #include <sys/signalvar.h> 86 #include <sys/vnode.h> 87 #include <sys/vmmeter.h> 88 #include <sys/sx.h> 89 #include <sys/sysctl.h> 90 91 #include <vm/vm.h> 92 #include <vm/vm_param.h> 93 #include <vm/vm_object.h> 94 #include <vm/vm_page.h> 95 #include <vm/vm_map.h> 96 #include <vm/vm_pageout.h> 97 #include <vm/vm_pager.h> 98 #include <vm/vm_zone.h> 99 #include <vm/swap_pager.h> 100 #include <vm/vm_extern.h> 101 102 #include <machine/mutex.h> 103 104 /* 105 * System initialization 106 */ 107 108 /* the kernel process "vm_pageout"*/ 109 static void vm_pageout __P((void)); 110 static int vm_pageout_clean __P((vm_page_t)); 111 static void vm_pageout_scan __P((int pass)); 112 static int vm_pageout_free_page_calc __P((vm_size_t count)); 113 struct proc *pageproc; 114 115 static struct kproc_desc page_kp = { 116 "pagedaemon", 117 vm_pageout, 118 &pageproc 119 }; 120 SYSINIT(pagedaemon, SI_SUB_KTHREAD_PAGE, SI_ORDER_FIRST, kproc_start, &page_kp) 121 122 #if !defined(NO_SWAPPING) 123 /* the kernel process "vm_daemon"*/ 124 static void vm_daemon __P((void)); 125 static struct proc *vmproc; 126 127 static struct kproc_desc vm_kp = { 128 "vmdaemon", 129 vm_daemon, 130 &vmproc 131 }; 132 SYSINIT(vmdaemon, SI_SUB_KTHREAD_VM, SI_ORDER_FIRST, kproc_start, &vm_kp) 133 #endif 134 135 136 int vm_pages_needed=0; /* Event on which pageout daemon sleeps */ 137 int vm_pageout_deficit=0; /* Estimated number of pages deficit */ 138 int vm_pageout_pages_needed=0; /* flag saying that the pageout daemon needs pages */ 139 140 #if !defined(NO_SWAPPING) 141 static int vm_pageout_req_swapout; /* XXX */ 142 static int vm_daemon_needed; 143 #endif 144 extern int vm_swap_size; 145 static int vm_max_launder = 32; 146 static int vm_pageout_stats_max=0, vm_pageout_stats_interval = 0; 147 static int vm_pageout_full_stats_interval = 0; 148 static int vm_pageout_stats_free_max=0, vm_pageout_algorithm=0; 149 static int defer_swap_pageouts=0; 150 static int disable_swap_pageouts=0; 151 152 #if defined(NO_SWAPPING) 153 static int vm_swap_enabled=0; 154 static int vm_swap_idle_enabled=0; 155 #else 156 static int vm_swap_enabled=1; 157 static int vm_swap_idle_enabled=0; 158 #endif 159 160 SYSCTL_INT(_vm, VM_PAGEOUT_ALGORITHM, pageout_algorithm, 161 CTLFLAG_RW, &vm_pageout_algorithm, 0, "LRU page mgmt"); 162 163 SYSCTL_INT(_vm, OID_AUTO, max_launder, 164 CTLFLAG_RW, &vm_max_launder, 0, "Limit dirty flushes in pageout"); 165 166 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_max, 167 CTLFLAG_RW, &vm_pageout_stats_max, 0, "Max pageout stats scan length"); 168 169 SYSCTL_INT(_vm, OID_AUTO, pageout_full_stats_interval, 170 CTLFLAG_RW, &vm_pageout_full_stats_interval, 0, "Interval for full stats scan"); 171 172 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_interval, 173 CTLFLAG_RW, &vm_pageout_stats_interval, 0, "Interval for partial stats scan"); 174 175 SYSCTL_INT(_vm, OID_AUTO, pageout_stats_free_max, 176 CTLFLAG_RW, &vm_pageout_stats_free_max, 0, "Not implemented"); 177 178 #if defined(NO_SWAPPING) 179 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 180 CTLFLAG_RD, &vm_swap_enabled, 0, ""); 181 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 182 CTLFLAG_RD, &vm_swap_idle_enabled, 0, ""); 183 #else 184 SYSCTL_INT(_vm, VM_SWAPPING_ENABLED, swap_enabled, 185 CTLFLAG_RW, &vm_swap_enabled, 0, "Enable entire process swapout"); 186 SYSCTL_INT(_vm, OID_AUTO, swap_idle_enabled, 187 CTLFLAG_RW, &vm_swap_idle_enabled, 0, "Allow swapout on idle criteria"); 188 #endif 189 190 SYSCTL_INT(_vm, OID_AUTO, defer_swapspace_pageouts, 191 CTLFLAG_RW, &defer_swap_pageouts, 0, "Give preference to dirty pages in mem"); 192 193 SYSCTL_INT(_vm, OID_AUTO, disable_swapspace_pageouts, 194 CTLFLAG_RW, &disable_swap_pageouts, 0, "Disallow swapout of dirty pages"); 195 196 #define VM_PAGEOUT_PAGE_COUNT 16 197 int vm_pageout_page_count = VM_PAGEOUT_PAGE_COUNT; 198 199 int vm_page_max_wired; /* XXX max # of wired pages system-wide */ 200 201 #if !defined(NO_SWAPPING) 202 typedef void freeer_fcn_t __P((vm_map_t, vm_object_t, vm_pindex_t, int)); 203 static void vm_pageout_map_deactivate_pages __P((vm_map_t, vm_pindex_t)); 204 static freeer_fcn_t vm_pageout_object_deactivate_pages; 205 static void vm_req_vmdaemon __P((void)); 206 #endif 207 static void vm_pageout_page_stats(void); 208 209 /* 210 * vm_pageout_clean: 211 * 212 * Clean the page and remove it from the laundry. 213 * 214 * We set the busy bit to cause potential page faults on this page to 215 * block. Note the careful timing, however, the busy bit isn't set till 216 * late and we cannot do anything that will mess with the page. 217 */ 218 219 static int 220 vm_pageout_clean(m) 221 vm_page_t m; 222 { 223 vm_object_t object; 224 vm_page_t mc[2*vm_pageout_page_count]; 225 int pageout_count; 226 int ib, is, page_base; 227 vm_pindex_t pindex = m->pindex; 228 229 GIANT_REQUIRED; 230 231 object = m->object; 232 233 /* 234 * It doesn't cost us anything to pageout OBJT_DEFAULT or OBJT_SWAP 235 * with the new swapper, but we could have serious problems paging 236 * out other object types if there is insufficient memory. 237 * 238 * Unfortunately, checking free memory here is far too late, so the 239 * check has been moved up a procedural level. 240 */ 241 242 /* 243 * Don't mess with the page if it's busy, held, or special 244 */ 245 if ((m->hold_count != 0) || 246 ((m->busy != 0) || (m->flags & (PG_BUSY|PG_UNMANAGED)))) { 247 return 0; 248 } 249 250 mc[vm_pageout_page_count] = m; 251 pageout_count = 1; 252 page_base = vm_pageout_page_count; 253 ib = 1; 254 is = 1; 255 256 /* 257 * Scan object for clusterable pages. 258 * 259 * We can cluster ONLY if: ->> the page is NOT 260 * clean, wired, busy, held, or mapped into a 261 * buffer, and one of the following: 262 * 1) The page is inactive, or a seldom used 263 * active page. 264 * -or- 265 * 2) we force the issue. 266 * 267 * During heavy mmap/modification loads the pageout 268 * daemon can really fragment the underlying file 269 * due to flushing pages out of order and not trying 270 * align the clusters (which leave sporatic out-of-order 271 * holes). To solve this problem we do the reverse scan 272 * first and attempt to align our cluster, then do a 273 * forward scan if room remains. 274 */ 275 276 more: 277 while (ib && pageout_count < vm_pageout_page_count) { 278 vm_page_t p; 279 280 if (ib > pindex) { 281 ib = 0; 282 break; 283 } 284 285 if ((p = vm_page_lookup(object, pindex - ib)) == NULL) { 286 ib = 0; 287 break; 288 } 289 if (((p->queue - p->pc) == PQ_CACHE) || 290 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 291 ib = 0; 292 break; 293 } 294 vm_page_test_dirty(p); 295 if ((p->dirty & p->valid) == 0 || 296 p->queue != PQ_INACTIVE || 297 p->wire_count != 0 || /* may be held by buf cache */ 298 p->hold_count != 0) { /* may be undergoing I/O */ 299 ib = 0; 300 break; 301 } 302 mc[--page_base] = p; 303 ++pageout_count; 304 ++ib; 305 /* 306 * alignment boundry, stop here and switch directions. Do 307 * not clear ib. 308 */ 309 if ((pindex - (ib - 1)) % vm_pageout_page_count == 0) 310 break; 311 } 312 313 while (pageout_count < vm_pageout_page_count && 314 pindex + is < object->size) { 315 vm_page_t p; 316 317 if ((p = vm_page_lookup(object, pindex + is)) == NULL) 318 break; 319 if (((p->queue - p->pc) == PQ_CACHE) || 320 (p->flags & (PG_BUSY|PG_UNMANAGED)) || p->busy) { 321 break; 322 } 323 vm_page_test_dirty(p); 324 if ((p->dirty & p->valid) == 0 || 325 p->queue != PQ_INACTIVE || 326 p->wire_count != 0 || /* may be held by buf cache */ 327 p->hold_count != 0) { /* may be undergoing I/O */ 328 break; 329 } 330 mc[page_base + pageout_count] = p; 331 ++pageout_count; 332 ++is; 333 } 334 335 /* 336 * If we exhausted our forward scan, continue with the reverse scan 337 * when possible, even past a page boundry. This catches boundry 338 * conditions. 339 */ 340 if (ib && pageout_count < vm_pageout_page_count) 341 goto more; 342 343 /* 344 * we allow reads during pageouts... 345 */ 346 return vm_pageout_flush(&mc[page_base], pageout_count, 0); 347 } 348 349 /* 350 * vm_pageout_flush() - launder the given pages 351 * 352 * The given pages are laundered. Note that we setup for the start of 353 * I/O ( i.e. busy the page ), mark it read-only, and bump the object 354 * reference count all in here rather then in the parent. If we want 355 * the parent to do more sophisticated things we may have to change 356 * the ordering. 357 */ 358 359 int 360 vm_pageout_flush(mc, count, flags) 361 vm_page_t *mc; 362 int count; 363 int flags; 364 { 365 vm_object_t object; 366 int pageout_status[count]; 367 int numpagedout = 0; 368 int i; 369 370 GIANT_REQUIRED; 371 /* 372 * Initiate I/O. Bump the vm_page_t->busy counter and 373 * mark the pages read-only. 374 * 375 * We do not have to fixup the clean/dirty bits here... we can 376 * allow the pager to do it after the I/O completes. 377 * 378 * NOTE! mc[i]->dirty may be partial or fragmented due to an 379 * edge case with file fragments. 380 */ 381 382 for (i = 0; i < count; i++) { 383 KASSERT(mc[i]->valid == VM_PAGE_BITS_ALL, ("vm_pageout_flush page %p index %d/%d: partially invalid page", mc[i], i, count)); 384 vm_page_io_start(mc[i]); 385 vm_page_protect(mc[i], VM_PROT_READ); 386 } 387 388 object = mc[0]->object; 389 vm_object_pip_add(object, count); 390 391 vm_pager_put_pages(object, mc, count, 392 (flags | ((object == kernel_object) ? OBJPC_SYNC : 0)), 393 pageout_status); 394 395 for (i = 0; i < count; i++) { 396 vm_page_t mt = mc[i]; 397 398 switch (pageout_status[i]) { 399 case VM_PAGER_OK: 400 numpagedout++; 401 break; 402 case VM_PAGER_PEND: 403 numpagedout++; 404 break; 405 case VM_PAGER_BAD: 406 /* 407 * Page outside of range of object. Right now we 408 * essentially lose the changes by pretending it 409 * worked. 410 */ 411 pmap_clear_modify(mt); 412 vm_page_undirty(mt); 413 break; 414 case VM_PAGER_ERROR: 415 case VM_PAGER_FAIL: 416 /* 417 * If page couldn't be paged out, then reactivate the 418 * page so it doesn't clog the inactive list. (We 419 * will try paging out it again later). 420 */ 421 vm_page_activate(mt); 422 break; 423 case VM_PAGER_AGAIN: 424 break; 425 } 426 427 /* 428 * If the operation is still going, leave the page busy to 429 * block all other accesses. Also, leave the paging in 430 * progress indicator set so that we don't attempt an object 431 * collapse. 432 */ 433 if (pageout_status[i] != VM_PAGER_PEND) { 434 vm_object_pip_wakeup(object); 435 vm_page_io_finish(mt); 436 if (!vm_page_count_severe() || !vm_page_try_to_cache(mt)) 437 vm_page_protect(mt, VM_PROT_READ); 438 } 439 } 440 return numpagedout; 441 } 442 443 #if !defined(NO_SWAPPING) 444 /* 445 * vm_pageout_object_deactivate_pages 446 * 447 * deactivate enough pages to satisfy the inactive target 448 * requirements or if vm_page_proc_limit is set, then 449 * deactivate all of the pages in the object and its 450 * backing_objects. 451 * 452 * The object and map must be locked. 453 */ 454 static void 455 vm_pageout_object_deactivate_pages(map, object, desired, map_remove_only) 456 vm_map_t map; 457 vm_object_t object; 458 vm_pindex_t desired; 459 int map_remove_only; 460 { 461 vm_page_t p, next; 462 int rcount; 463 int remove_mode; 464 465 GIANT_REQUIRED; 466 if (object->type == OBJT_DEVICE || object->type == OBJT_PHYS) 467 return; 468 469 while (object) { 470 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 471 return; 472 if (object->paging_in_progress) 473 return; 474 475 remove_mode = map_remove_only; 476 if (object->shadow_count > 1) 477 remove_mode = 1; 478 /* 479 * scan the objects entire memory queue 480 */ 481 rcount = object->resident_page_count; 482 p = TAILQ_FIRST(&object->memq); 483 while (p && (rcount-- > 0)) { 484 int actcount; 485 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 486 return; 487 next = TAILQ_NEXT(p, listq); 488 cnt.v_pdpages++; 489 if (p->wire_count != 0 || 490 p->hold_count != 0 || 491 p->busy != 0 || 492 (p->flags & (PG_BUSY|PG_UNMANAGED)) || 493 !pmap_page_exists(vm_map_pmap(map), p)) { 494 p = next; 495 continue; 496 } 497 498 actcount = pmap_ts_referenced(p); 499 if (actcount) { 500 vm_page_flag_set(p, PG_REFERENCED); 501 } else if (p->flags & PG_REFERENCED) { 502 actcount = 1; 503 } 504 505 if ((p->queue != PQ_ACTIVE) && 506 (p->flags & PG_REFERENCED)) { 507 vm_page_activate(p); 508 p->act_count += actcount; 509 vm_page_flag_clear(p, PG_REFERENCED); 510 } else if (p->queue == PQ_ACTIVE) { 511 if ((p->flags & PG_REFERENCED) == 0) { 512 p->act_count -= min(p->act_count, ACT_DECLINE); 513 if (!remove_mode && (vm_pageout_algorithm || (p->act_count == 0))) { 514 vm_page_protect(p, VM_PROT_NONE); 515 vm_page_deactivate(p); 516 } else { 517 vm_pageq_requeue(p); 518 } 519 } else { 520 vm_page_activate(p); 521 vm_page_flag_clear(p, PG_REFERENCED); 522 if (p->act_count < (ACT_MAX - ACT_ADVANCE)) 523 p->act_count += ACT_ADVANCE; 524 vm_pageq_requeue(p); 525 } 526 } else if (p->queue == PQ_INACTIVE) { 527 vm_page_protect(p, VM_PROT_NONE); 528 } 529 p = next; 530 } 531 object = object->backing_object; 532 } 533 return; 534 } 535 536 /* 537 * deactivate some number of pages in a map, try to do it fairly, but 538 * that is really hard to do. 539 */ 540 static void 541 vm_pageout_map_deactivate_pages(map, desired) 542 vm_map_t map; 543 vm_pindex_t desired; 544 { 545 vm_map_entry_t tmpe; 546 vm_object_t obj, bigobj; 547 int nothingwired; 548 549 GIANT_REQUIRED; 550 if (lockmgr(&map->lock, LK_EXCLUSIVE | LK_NOWAIT, (void *)0, curthread)) { 551 return; 552 } 553 554 bigobj = NULL; 555 nothingwired = TRUE; 556 557 /* 558 * first, search out the biggest object, and try to free pages from 559 * that. 560 */ 561 tmpe = map->header.next; 562 while (tmpe != &map->header) { 563 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 564 obj = tmpe->object.vm_object; 565 if ((obj != NULL) && (obj->shadow_count <= 1) && 566 ((bigobj == NULL) || 567 (bigobj->resident_page_count < obj->resident_page_count))) { 568 bigobj = obj; 569 } 570 } 571 if (tmpe->wired_count > 0) 572 nothingwired = FALSE; 573 tmpe = tmpe->next; 574 } 575 576 if (bigobj) 577 vm_pageout_object_deactivate_pages(map, bigobj, desired, 0); 578 579 /* 580 * Next, hunt around for other pages to deactivate. We actually 581 * do this search sort of wrong -- .text first is not the best idea. 582 */ 583 tmpe = map->header.next; 584 while (tmpe != &map->header) { 585 if (pmap_resident_count(vm_map_pmap(map)) <= desired) 586 break; 587 if ((tmpe->eflags & MAP_ENTRY_IS_SUB_MAP) == 0) { 588 obj = tmpe->object.vm_object; 589 if (obj) 590 vm_pageout_object_deactivate_pages(map, obj, desired, 0); 591 } 592 tmpe = tmpe->next; 593 }; 594 595 /* 596 * Remove all mappings if a process is swapped out, this will free page 597 * table pages. 598 */ 599 if (desired == 0 && nothingwired) 600 pmap_remove(vm_map_pmap(map), 601 VM_MIN_ADDRESS, VM_MAXUSER_ADDRESS); 602 vm_map_unlock(map); 603 return; 604 } 605 #endif 606 607 /* 608 * Don't try to be fancy - being fancy can lead to VOP_LOCK's and therefore 609 * to vnode deadlocks. We only do it for OBJT_DEFAULT and OBJT_SWAP objects 610 * which we know can be trivially freed. 611 */ 612 613 void 614 vm_pageout_page_free(vm_page_t m) { 615 vm_object_t object = m->object; 616 int type = object->type; 617 618 GIANT_REQUIRED; 619 if (type == OBJT_SWAP || type == OBJT_DEFAULT) 620 vm_object_reference(object); 621 vm_page_busy(m); 622 vm_page_protect(m, VM_PROT_NONE); 623 vm_page_free(m); 624 if (type == OBJT_SWAP || type == OBJT_DEFAULT) 625 vm_object_deallocate(object); 626 } 627 628 /* 629 * vm_pageout_scan does the dirty work for the pageout daemon. 630 */ 631 static void 632 vm_pageout_scan(int pass) 633 { 634 vm_page_t m, next; 635 struct vm_page marker; 636 int save_page_shortage; 637 int save_inactive_count; 638 int page_shortage, maxscan, pcount; 639 int addl_page_shortage, addl_page_shortage_init; 640 struct proc *p, *bigproc; 641 vm_offset_t size, bigsize; 642 vm_object_t object; 643 int actcount; 644 int vnodes_skipped = 0; 645 int maxlaunder; 646 int s; 647 648 GIANT_REQUIRED; 649 /* 650 * Do whatever cleanup that the pmap code can. 651 */ 652 pmap_collect(); 653 654 addl_page_shortage_init = vm_pageout_deficit; 655 vm_pageout_deficit = 0; 656 657 /* 658 * Calculate the number of pages we want to either free or move 659 * to the cache. 660 */ 661 page_shortage = vm_paging_target() + addl_page_shortage_init; 662 save_page_shortage = page_shortage; 663 save_inactive_count = cnt.v_inactive_count; 664 665 /* 666 * Initialize our marker 667 */ 668 bzero(&marker, sizeof(marker)); 669 marker.flags = PG_BUSY | PG_FICTITIOUS | PG_MARKER; 670 marker.queue = PQ_INACTIVE; 671 marker.wire_count = 1; 672 673 /* 674 * Start scanning the inactive queue for pages we can move to the 675 * cache or free. The scan will stop when the target is reached or 676 * we have scanned the entire inactive queue. Note that m->act_count 677 * is not used to form decisions for the inactive queue, only for the 678 * active queue. 679 * 680 * maxlaunder limits the number of dirty pages we flush per scan. 681 * For most systems a smaller value (16 or 32) is more robust under 682 * extreme memory and disk pressure because any unnecessary writes 683 * to disk can result in extreme performance degredation. However, 684 * systems with excessive dirty pages (especially when MAP_NOSYNC is 685 * used) will die horribly with limited laundering. If the pageout 686 * daemon cannot clean enough pages in the first pass, we let it go 687 * all out in succeeding passes. 688 */ 689 690 if ((maxlaunder = vm_max_launder) <= 1) 691 maxlaunder = 1; 692 if (pass) 693 maxlaunder = 10000; 694 695 rescan0: 696 addl_page_shortage = addl_page_shortage_init; 697 maxscan = cnt.v_inactive_count; 698 699 for (m = TAILQ_FIRST(&vm_page_queues[PQ_INACTIVE].pl); 700 m != NULL && maxscan-- > 0 && page_shortage > 0; 701 m = next) { 702 703 cnt.v_pdpages++; 704 705 if (m->queue != PQ_INACTIVE) { 706 goto rescan0; 707 } 708 709 next = TAILQ_NEXT(m, pageq); 710 711 /* 712 * skip marker pages 713 */ 714 if (m->flags & PG_MARKER) 715 continue; 716 717 /* 718 * A held page may be undergoing I/O, so skip it. 719 */ 720 if (m->hold_count) { 721 vm_pageq_requeue(m); 722 addl_page_shortage++; 723 continue; 724 } 725 /* 726 * Dont mess with busy pages, keep in the front of the 727 * queue, most likely are being paged out. 728 */ 729 if (m->busy || (m->flags & PG_BUSY)) { 730 addl_page_shortage++; 731 continue; 732 } 733 734 /* 735 * If the object is not being used, we ignore previous 736 * references. 737 */ 738 if (m->object->ref_count == 0) { 739 vm_page_flag_clear(m, PG_REFERENCED); 740 pmap_clear_reference(m); 741 742 /* 743 * Otherwise, if the page has been referenced while in the 744 * inactive queue, we bump the "activation count" upwards, 745 * making it less likely that the page will be added back to 746 * the inactive queue prematurely again. Here we check the 747 * page tables (or emulated bits, if any), given the upper 748 * level VM system not knowing anything about existing 749 * references. 750 */ 751 } else if (((m->flags & PG_REFERENCED) == 0) && 752 (actcount = pmap_ts_referenced(m))) { 753 vm_page_activate(m); 754 m->act_count += (actcount + ACT_ADVANCE); 755 continue; 756 } 757 758 /* 759 * If the upper level VM system knows about any page 760 * references, we activate the page. We also set the 761 * "activation count" higher than normal so that we will less 762 * likely place pages back onto the inactive queue again. 763 */ 764 if ((m->flags & PG_REFERENCED) != 0) { 765 vm_page_flag_clear(m, PG_REFERENCED); 766 actcount = pmap_ts_referenced(m); 767 vm_page_activate(m); 768 m->act_count += (actcount + ACT_ADVANCE + 1); 769 continue; 770 } 771 772 /* 773 * If the upper level VM system doesn't know anything about 774 * the page being dirty, we have to check for it again. As 775 * far as the VM code knows, any partially dirty pages are 776 * fully dirty. 777 */ 778 if (m->dirty == 0) { 779 vm_page_test_dirty(m); 780 } else { 781 vm_page_dirty(m); 782 } 783 784 /* 785 * Invalid pages can be easily freed 786 */ 787 if (m->valid == 0) { 788 vm_pageout_page_free(m); 789 cnt.v_dfree++; 790 --page_shortage; 791 792 /* 793 * Clean pages can be placed onto the cache queue. This 794 * effectively frees them. 795 */ 796 } else if (m->dirty == 0) { 797 vm_page_cache(m); 798 --page_shortage; 799 } else if ((m->flags & PG_WINATCFLS) == 0 && pass == 0) { 800 /* 801 * Dirty pages need to be paged out, but flushing 802 * a page is extremely expensive verses freeing 803 * a clean page. Rather then artificially limiting 804 * the number of pages we can flush, we instead give 805 * dirty pages extra priority on the inactive queue 806 * by forcing them to be cycled through the queue 807 * twice before being flushed, after which the 808 * (now clean) page will cycle through once more 809 * before being freed. This significantly extends 810 * the thrash point for a heavily loaded machine. 811 */ 812 vm_page_flag_set(m, PG_WINATCFLS); 813 vm_pageq_requeue(m); 814 } else if (maxlaunder > 0) { 815 /* 816 * We always want to try to flush some dirty pages if 817 * we encounter them, to keep the system stable. 818 * Normally this number is small, but under extreme 819 * pressure where there are insufficient clean pages 820 * on the inactive queue, we may have to go all out. 821 */ 822 int swap_pageouts_ok; 823 struct vnode *vp = NULL; 824 struct mount *mp; 825 826 object = m->object; 827 828 if ((object->type != OBJT_SWAP) && (object->type != OBJT_DEFAULT)) { 829 swap_pageouts_ok = 1; 830 } else { 831 swap_pageouts_ok = !(defer_swap_pageouts || disable_swap_pageouts); 832 swap_pageouts_ok |= (!disable_swap_pageouts && defer_swap_pageouts && 833 vm_page_count_min()); 834 835 } 836 837 /* 838 * We don't bother paging objects that are "dead". 839 * Those objects are in a "rundown" state. 840 */ 841 if (!swap_pageouts_ok || (object->flags & OBJ_DEAD)) { 842 vm_pageq_requeue(m); 843 continue; 844 } 845 846 /* 847 * The object is already known NOT to be dead. It 848 * is possible for the vget() to block the whole 849 * pageout daemon, but the new low-memory handling 850 * code should prevent it. 851 * 852 * The previous code skipped locked vnodes and, worse, 853 * reordered pages in the queue. This results in 854 * completely non-deterministic operation and, on a 855 * busy system, can lead to extremely non-optimal 856 * pageouts. For example, it can cause clean pages 857 * to be freed and dirty pages to be moved to the end 858 * of the queue. Since dirty pages are also moved to 859 * the end of the queue once-cleaned, this gives 860 * way too large a weighting to defering the freeing 861 * of dirty pages. 862 * 863 * XXX we need to be able to apply a timeout to the 864 * vget() lock attempt. 865 */ 866 867 if (object->type == OBJT_VNODE) { 868 vp = object->handle; 869 870 mp = NULL; 871 if (vp->v_type == VREG) 872 vn_start_write(vp, &mp, V_NOWAIT); 873 if (vget(vp, LK_EXCLUSIVE|LK_NOOBJ, curthread)) { 874 vn_finished_write(mp); 875 if (object->flags & OBJ_MIGHTBEDIRTY) 876 vnodes_skipped++; 877 continue; 878 } 879 880 /* 881 * The page might have been moved to another 882 * queue during potential blocking in vget() 883 * above. The page might have been freed and 884 * reused for another vnode. The object might 885 * have been reused for another vnode. 886 */ 887 if (m->queue != PQ_INACTIVE || 888 m->object != object || 889 object->handle != vp) { 890 if (object->flags & OBJ_MIGHTBEDIRTY) 891 vnodes_skipped++; 892 vput(vp); 893 vn_finished_write(mp); 894 continue; 895 } 896 897 /* 898 * The page may have been busied during the 899 * blocking in vput(); We don't move the 900 * page back onto the end of the queue so that 901 * statistics are more correct if we don't. 902 */ 903 if (m->busy || (m->flags & PG_BUSY)) { 904 vput(vp); 905 vn_finished_write(mp); 906 continue; 907 } 908 909 /* 910 * If the page has become held it might 911 * be undergoing I/O, so skip it 912 */ 913 if (m->hold_count) { 914 vm_pageq_requeue(m); 915 if (object->flags & OBJ_MIGHTBEDIRTY) 916 vnodes_skipped++; 917 vput(vp); 918 vn_finished_write(mp); 919 continue; 920 } 921 } 922 923 /* 924 * If a page is dirty, then it is either being washed 925 * (but not yet cleaned) or it is still in the 926 * laundry. If it is still in the laundry, then we 927 * start the cleaning operation. 928 * 929 * This operation may cluster, invalidating the 'next' 930 * pointer. To prevent an inordinate number of 931 * restarts we use our marker to remember our place. 932 * 933 * decrement page_shortage on success to account for 934 * the (future) cleaned page. Otherwise we could wind 935 * up laundering or cleaning too many pages. 936 */ 937 s = splvm(); 938 TAILQ_INSERT_AFTER(&vm_page_queues[PQ_INACTIVE].pl, m, &marker, pageq); 939 splx(s); 940 if (vm_pageout_clean(m) != 0) { 941 --page_shortage; 942 --maxlaunder; 943 } 944 s = splvm(); 945 next = TAILQ_NEXT(&marker, pageq); 946 TAILQ_REMOVE(&vm_page_queues[PQ_INACTIVE].pl, &marker, pageq); 947 splx(s); 948 if (vp) { 949 vput(vp); 950 vn_finished_write(mp); 951 } 952 } 953 } 954 955 /* 956 * Compute the number of pages we want to try to move from the 957 * active queue to the inactive queue. 958 */ 959 page_shortage = vm_paging_target() + 960 cnt.v_inactive_target - cnt.v_inactive_count; 961 page_shortage += addl_page_shortage; 962 963 /* 964 * Scan the active queue for things we can deactivate. We nominally 965 * track the per-page activity counter and use it to locate 966 * deactivation candidates. 967 */ 968 969 pcount = cnt.v_active_count; 970 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 971 972 while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) { 973 974 /* 975 * This is a consistency check, and should likely be a panic 976 * or warning. 977 */ 978 if (m->queue != PQ_ACTIVE) { 979 break; 980 } 981 982 next = TAILQ_NEXT(m, pageq); 983 /* 984 * Don't deactivate pages that are busy. 985 */ 986 if ((m->busy != 0) || 987 (m->flags & PG_BUSY) || 988 (m->hold_count != 0)) { 989 vm_pageq_requeue(m); 990 m = next; 991 continue; 992 } 993 994 /* 995 * The count for pagedaemon pages is done after checking the 996 * page for eligibility... 997 */ 998 cnt.v_pdpages++; 999 1000 /* 1001 * Check to see "how much" the page has been used. 1002 */ 1003 actcount = 0; 1004 if (m->object->ref_count != 0) { 1005 if (m->flags & PG_REFERENCED) { 1006 actcount += 1; 1007 } 1008 actcount += pmap_ts_referenced(m); 1009 if (actcount) { 1010 m->act_count += ACT_ADVANCE + actcount; 1011 if (m->act_count > ACT_MAX) 1012 m->act_count = ACT_MAX; 1013 } 1014 } 1015 1016 /* 1017 * Since we have "tested" this bit, we need to clear it now. 1018 */ 1019 vm_page_flag_clear(m, PG_REFERENCED); 1020 1021 /* 1022 * Only if an object is currently being used, do we use the 1023 * page activation count stats. 1024 */ 1025 if (actcount && (m->object->ref_count != 0)) { 1026 vm_pageq_requeue(m); 1027 } else { 1028 m->act_count -= min(m->act_count, ACT_DECLINE); 1029 if (vm_pageout_algorithm || 1030 m->object->ref_count == 0 || 1031 m->act_count == 0) { 1032 page_shortage--; 1033 if (m->object->ref_count == 0) { 1034 vm_page_protect(m, VM_PROT_NONE); 1035 if (m->dirty == 0) 1036 vm_page_cache(m); 1037 else 1038 vm_page_deactivate(m); 1039 } else { 1040 vm_page_deactivate(m); 1041 } 1042 } else { 1043 vm_pageq_requeue(m); 1044 } 1045 } 1046 m = next; 1047 } 1048 1049 s = splvm(); 1050 1051 /* 1052 * We try to maintain some *really* free pages, this allows interrupt 1053 * code to be guaranteed space. Since both cache and free queues 1054 * are considered basically 'free', moving pages from cache to free 1055 * does not effect other calculations. 1056 */ 1057 1058 while (cnt.v_free_count < cnt.v_free_reserved) { 1059 static int cache_rover = 0; 1060 m = vm_pageq_find(PQ_CACHE, cache_rover, FALSE); 1061 if (!m) 1062 break; 1063 if ((m->flags & (PG_BUSY|PG_UNMANAGED)) || 1064 m->busy || 1065 m->hold_count || 1066 m->wire_count) { 1067 #ifdef INVARIANTS 1068 printf("Warning: busy page %p found in cache\n", m); 1069 #endif 1070 vm_page_deactivate(m); 1071 continue; 1072 } 1073 cache_rover = (cache_rover + PQ_PRIME2) & PQ_L2_MASK; 1074 vm_pageout_page_free(m); 1075 cnt.v_dfree++; 1076 } 1077 splx(s); 1078 1079 #if !defined(NO_SWAPPING) 1080 /* 1081 * Idle process swapout -- run once per second. 1082 */ 1083 if (vm_swap_idle_enabled) { 1084 static long lsec; 1085 if (time_second != lsec) { 1086 vm_pageout_req_swapout |= VM_SWAP_IDLE; 1087 vm_req_vmdaemon(); 1088 lsec = time_second; 1089 } 1090 } 1091 #endif 1092 1093 /* 1094 * If we didn't get enough free pages, and we have skipped a vnode 1095 * in a writeable object, wakeup the sync daemon. And kick swapout 1096 * if we did not get enough free pages. 1097 */ 1098 if (vm_paging_target() > 0) { 1099 if (vnodes_skipped && vm_page_count_min()) 1100 (void) speedup_syncer(); 1101 #if !defined(NO_SWAPPING) 1102 if (vm_swap_enabled && vm_page_count_target()) { 1103 vm_req_vmdaemon(); 1104 vm_pageout_req_swapout |= VM_SWAP_NORMAL; 1105 } 1106 #endif 1107 } 1108 1109 /* 1110 * If we are out of swap and were not able to reach our paging 1111 * target, kill the largest process. 1112 * 1113 * We keep the process bigproc locked once we find it to keep anyone 1114 * from messing with it; however, there is a possibility of 1115 * deadlock if process B is bigproc and one of it's child processes 1116 * attempts to propagate a signal to B while we are waiting for A's 1117 * lock while walking this list. To avoid this, we don't block on 1118 * the process lock but just skip a process if it is already locked. 1119 */ 1120 if ((vm_swap_size < 64 && vm_page_count_min()) || 1121 (swap_pager_full && vm_paging_target() > 0)) { 1122 #if 0 1123 if ((vm_swap_size < 64 || swap_pager_full) && vm_page_count_min()) { 1124 #endif 1125 bigproc = NULL; 1126 bigsize = 0; 1127 sx_slock(&allproc_lock); 1128 LIST_FOREACH(p, &allproc, p_list) { 1129 /* 1130 * If this process is already locked, skip it. 1131 */ 1132 if (PROC_TRYLOCK(p) == 0) 1133 continue; 1134 /* 1135 * if this is a system process, skip it 1136 */ 1137 if ((p->p_flag & P_SYSTEM) || (p->p_lock > 0) || 1138 (p->p_pid == 1) || 1139 ((p->p_pid < 48) && (vm_swap_size != 0))) { 1140 PROC_UNLOCK(p); 1141 continue; 1142 } 1143 /* 1144 * if the process is in a non-running type state, 1145 * don't touch it. 1146 */ 1147 mtx_lock_spin(&sched_lock); 1148 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 1149 mtx_unlock_spin(&sched_lock); 1150 PROC_UNLOCK(p); 1151 continue; 1152 } 1153 mtx_unlock_spin(&sched_lock); 1154 /* 1155 * get the process size 1156 */ 1157 size = vmspace_resident_count(p->p_vmspace) + 1158 vmspace_swap_count(p->p_vmspace); 1159 /* 1160 * if the this process is bigger than the biggest one 1161 * remember it. 1162 */ 1163 if (size > bigsize) { 1164 if (bigproc != NULL) 1165 PROC_UNLOCK(bigproc); 1166 bigproc = p; 1167 bigsize = size; 1168 } else 1169 PROC_UNLOCK(p); 1170 } 1171 sx_sunlock(&allproc_lock); 1172 if (bigproc != NULL) { 1173 struct ksegrp *kg; 1174 killproc(bigproc, "out of swap space"); 1175 mtx_lock_spin(&sched_lock); 1176 FOREACH_KSEGRP_IN_PROC(bigproc, kg) { 1177 kg->kg_estcpu = 0; 1178 kg->kg_nice = PRIO_MIN; /* XXXKSE ??? */ 1179 resetpriority(kg); 1180 } 1181 mtx_unlock_spin(&sched_lock); 1182 PROC_UNLOCK(bigproc); 1183 wakeup(&cnt.v_free_count); 1184 } 1185 } 1186 } 1187 1188 /* 1189 * This routine tries to maintain the pseudo LRU active queue, 1190 * so that during long periods of time where there is no paging, 1191 * that some statistic accumulation still occurs. This code 1192 * helps the situation where paging just starts to occur. 1193 */ 1194 static void 1195 vm_pageout_page_stats() 1196 { 1197 vm_page_t m,next; 1198 int pcount,tpcount; /* Number of pages to check */ 1199 static int fullintervalcount = 0; 1200 int page_shortage; 1201 int s0; 1202 1203 page_shortage = 1204 (cnt.v_inactive_target + cnt.v_cache_max + cnt.v_free_min) - 1205 (cnt.v_free_count + cnt.v_inactive_count + cnt.v_cache_count); 1206 1207 if (page_shortage <= 0) 1208 return; 1209 1210 s0 = splvm(); 1211 1212 pcount = cnt.v_active_count; 1213 fullintervalcount += vm_pageout_stats_interval; 1214 if (fullintervalcount < vm_pageout_full_stats_interval) { 1215 tpcount = (vm_pageout_stats_max * cnt.v_active_count) / cnt.v_page_count; 1216 if (pcount > tpcount) 1217 pcount = tpcount; 1218 } else { 1219 fullintervalcount = 0; 1220 } 1221 1222 m = TAILQ_FIRST(&vm_page_queues[PQ_ACTIVE].pl); 1223 while ((m != NULL) && (pcount-- > 0)) { 1224 int actcount; 1225 1226 if (m->queue != PQ_ACTIVE) { 1227 break; 1228 } 1229 1230 next = TAILQ_NEXT(m, pageq); 1231 /* 1232 * Don't deactivate pages that are busy. 1233 */ 1234 if ((m->busy != 0) || 1235 (m->flags & PG_BUSY) || 1236 (m->hold_count != 0)) { 1237 vm_pageq_requeue(m); 1238 m = next; 1239 continue; 1240 } 1241 1242 actcount = 0; 1243 if (m->flags & PG_REFERENCED) { 1244 vm_page_flag_clear(m, PG_REFERENCED); 1245 actcount += 1; 1246 } 1247 1248 actcount += pmap_ts_referenced(m); 1249 if (actcount) { 1250 m->act_count += ACT_ADVANCE + actcount; 1251 if (m->act_count > ACT_MAX) 1252 m->act_count = ACT_MAX; 1253 vm_pageq_requeue(m); 1254 } else { 1255 if (m->act_count == 0) { 1256 /* 1257 * We turn off page access, so that we have 1258 * more accurate RSS stats. We don't do this 1259 * in the normal page deactivation when the 1260 * system is loaded VM wise, because the 1261 * cost of the large number of page protect 1262 * operations would be higher than the value 1263 * of doing the operation. 1264 */ 1265 vm_page_protect(m, VM_PROT_NONE); 1266 vm_page_deactivate(m); 1267 } else { 1268 m->act_count -= min(m->act_count, ACT_DECLINE); 1269 vm_pageq_requeue(m); 1270 } 1271 } 1272 1273 m = next; 1274 } 1275 splx(s0); 1276 } 1277 1278 static int 1279 vm_pageout_free_page_calc(count) 1280 vm_size_t count; 1281 { 1282 if (count < cnt.v_page_count) 1283 return 0; 1284 /* 1285 * free_reserved needs to include enough for the largest swap pager 1286 * structures plus enough for any pv_entry structs when paging. 1287 */ 1288 if (cnt.v_page_count > 1024) 1289 cnt.v_free_min = 4 + (cnt.v_page_count - 1024) / 200; 1290 else 1291 cnt.v_free_min = 4; 1292 cnt.v_pageout_free_min = (2*MAXBSIZE)/PAGE_SIZE + 1293 cnt.v_interrupt_free_min; 1294 cnt.v_free_reserved = vm_pageout_page_count + 1295 cnt.v_pageout_free_min + (count / 768) + PQ_L2_SIZE; 1296 cnt.v_free_severe = cnt.v_free_min / 2; 1297 cnt.v_free_min += cnt.v_free_reserved; 1298 cnt.v_free_severe += cnt.v_free_reserved; 1299 return 1; 1300 } 1301 1302 1303 /* 1304 * vm_pageout is the high level pageout daemon. 1305 */ 1306 static void 1307 vm_pageout() 1308 { 1309 int pass; 1310 1311 mtx_lock(&Giant); 1312 1313 /* 1314 * Initialize some paging parameters. 1315 */ 1316 1317 cnt.v_interrupt_free_min = 2; 1318 if (cnt.v_page_count < 2000) 1319 vm_pageout_page_count = 8; 1320 1321 vm_pageout_free_page_calc(cnt.v_page_count); 1322 /* 1323 * v_free_target and v_cache_min control pageout hysteresis. Note 1324 * that these are more a measure of the VM cache queue hysteresis 1325 * then the VM free queue. Specifically, v_free_target is the 1326 * high water mark (free+cache pages). 1327 * 1328 * v_free_reserved + v_cache_min (mostly means v_cache_min) is the 1329 * low water mark, while v_free_min is the stop. v_cache_min must 1330 * be big enough to handle memory needs while the pageout daemon 1331 * is signalled and run to free more pages. 1332 */ 1333 if (cnt.v_free_count > 6144) 1334 cnt.v_free_target = 4 * cnt.v_free_min + cnt.v_free_reserved; 1335 else 1336 cnt.v_free_target = 2 * cnt.v_free_min + cnt.v_free_reserved; 1337 1338 if (cnt.v_free_count > 2048) { 1339 cnt.v_cache_min = cnt.v_free_target; 1340 cnt.v_cache_max = 2 * cnt.v_cache_min; 1341 cnt.v_inactive_target = (3 * cnt.v_free_target) / 2; 1342 } else { 1343 cnt.v_cache_min = 0; 1344 cnt.v_cache_max = 0; 1345 cnt.v_inactive_target = cnt.v_free_count / 4; 1346 } 1347 if (cnt.v_inactive_target > cnt.v_free_count / 3) 1348 cnt.v_inactive_target = cnt.v_free_count / 3; 1349 1350 /* XXX does not really belong here */ 1351 if (vm_page_max_wired == 0) 1352 vm_page_max_wired = cnt.v_free_count / 3; 1353 1354 if (vm_pageout_stats_max == 0) 1355 vm_pageout_stats_max = cnt.v_free_target; 1356 1357 /* 1358 * Set interval in seconds for stats scan. 1359 */ 1360 if (vm_pageout_stats_interval == 0) 1361 vm_pageout_stats_interval = 5; 1362 if (vm_pageout_full_stats_interval == 0) 1363 vm_pageout_full_stats_interval = vm_pageout_stats_interval * 4; 1364 1365 1366 /* 1367 * Set maximum free per pass 1368 */ 1369 if (vm_pageout_stats_free_max == 0) 1370 vm_pageout_stats_free_max = 5; 1371 1372 PROC_LOCK(curthread->td_proc); 1373 curthread->td_proc->p_flag |= P_BUFEXHAUST; 1374 PROC_UNLOCK(curthread->td_proc); 1375 swap_pager_swap_init(); 1376 pass = 0; 1377 /* 1378 * The pageout daemon is never done, so loop forever. 1379 */ 1380 while (TRUE) { 1381 int error; 1382 int s = splvm(); 1383 1384 /* 1385 * If we have enough free memory, wakeup waiters. Do 1386 * not clear vm_pages_needed until we reach our target, 1387 * otherwise we may be woken up over and over again and 1388 * waste a lot of cpu. 1389 */ 1390 if (vm_pages_needed && !vm_page_count_min()) { 1391 if (vm_paging_needed() <= 0) 1392 vm_pages_needed = 0; 1393 wakeup(&cnt.v_free_count); 1394 } 1395 if (vm_pages_needed) { 1396 /* 1397 * Still not done, take a second pass without waiting 1398 * (unlimited dirty cleaning), otherwise sleep a bit 1399 * and try again. 1400 */ 1401 ++pass; 1402 if (pass > 1) 1403 tsleep(&vm_pages_needed, PVM, 1404 "psleep", hz/2); 1405 } else { 1406 /* 1407 * Good enough, sleep & handle stats. Prime the pass 1408 * for the next run. 1409 */ 1410 if (pass > 1) 1411 pass = 1; 1412 else 1413 pass = 0; 1414 error = tsleep(&vm_pages_needed, PVM, 1415 "psleep", vm_pageout_stats_interval * hz); 1416 if (error && !vm_pages_needed) { 1417 splx(s); 1418 pass = 0; 1419 vm_pageout_page_stats(); 1420 continue; 1421 } 1422 } 1423 1424 if (vm_pages_needed) 1425 cnt.v_pdwakeups++; 1426 splx(s); 1427 vm_pageout_scan(pass); 1428 vm_pageout_deficit = 0; 1429 } 1430 } 1431 1432 void 1433 pagedaemon_wakeup() 1434 { 1435 if (!vm_pages_needed && curthread->td_proc != pageproc) { 1436 vm_pages_needed++; 1437 wakeup(&vm_pages_needed); 1438 } 1439 } 1440 1441 #if !defined(NO_SWAPPING) 1442 static void 1443 vm_req_vmdaemon() 1444 { 1445 static int lastrun = 0; 1446 1447 if ((ticks > (lastrun + hz)) || (ticks < lastrun)) { 1448 wakeup(&vm_daemon_needed); 1449 lastrun = ticks; 1450 } 1451 } 1452 1453 static void 1454 vm_daemon() 1455 { 1456 struct proc *p; 1457 1458 mtx_lock(&Giant); 1459 while (TRUE) { 1460 tsleep(&vm_daemon_needed, PPAUSE, "psleep", 0); 1461 if (vm_pageout_req_swapout) { 1462 swapout_procs(vm_pageout_req_swapout); 1463 vm_pageout_req_swapout = 0; 1464 } 1465 /* 1466 * scan the processes for exceeding their rlimits or if 1467 * process is swapped out -- deactivate pages 1468 */ 1469 1470 sx_slock(&allproc_lock); 1471 LIST_FOREACH(p, &allproc, p_list) { 1472 vm_pindex_t limit, size; 1473 1474 /* 1475 * if this is a system process or if we have already 1476 * looked at this process, skip it. 1477 */ 1478 if (p->p_flag & (P_SYSTEM | P_WEXIT)) { 1479 continue; 1480 } 1481 /* 1482 * if the process is in a non-running type state, 1483 * don't touch it. 1484 */ 1485 mtx_lock_spin(&sched_lock); 1486 if (p->p_stat != SRUN && p->p_stat != SSLEEP) { 1487 mtx_unlock_spin(&sched_lock); 1488 continue; 1489 } 1490 /* 1491 * get a limit 1492 */ 1493 limit = OFF_TO_IDX( 1494 qmin(p->p_rlimit[RLIMIT_RSS].rlim_cur, 1495 p->p_rlimit[RLIMIT_RSS].rlim_max)); 1496 1497 /* 1498 * let processes that are swapped out really be 1499 * swapped out set the limit to nothing (will force a 1500 * swap-out.) 1501 */ 1502 if ((p->p_sflag & PS_INMEM) == 0) 1503 limit = 0; /* XXX */ 1504 mtx_unlock_spin(&sched_lock); 1505 1506 size = vmspace_resident_count(p->p_vmspace); 1507 if (limit >= 0 && size >= limit) { 1508 vm_pageout_map_deactivate_pages( 1509 &p->p_vmspace->vm_map, limit); 1510 } 1511 } 1512 sx_sunlock(&allproc_lock); 1513 } 1514 } 1515 #endif 1516